I'm just wondering about something as I design my WTC. Is it possible to pump air into a rubber bladder. And as it reverses so air goes back into the WTC to pump water into the chamber? Or is this just redundant and a waste of space and battery power?

Well I know, I miss more than hit With a face that was launched to sink.-Flogging Molly-

I really like the OTW dive modules. From both an engineering quality perspective as well as the type of ballast system used.

In my opinion these modules are well designed and crafted from quality materials. Of the many instances of these modules that I have either owned or am aware of, I do not recall hearing of any out-of-the-box problems...no leaks, no other fitment issues. Drop in your servos and receiver and it's good to go.

The water pump-based system provides a very good level of control over the level of ballast. It's not capable of the *exact* ballast control that a piston with appropriate electronics can do, but it is very close.

The one consideration that one needs to be aware of is that they only come in two diameters: 90mm and 110mm. This essentially limits use to medium to large boats.

The only thing that i can complain about is the acrylic tube, at this time. I have the OTW made for my 1/12th scale 32nd parallel USS Holland but haven't installed it yet. I bought it from a friend but when it arrived the tube was shattered. I'm planning to exchange the acrylic tube for a polycarbonate. I am going to use 3/8" wall aluminum tube for the ballast tank section with the polycarbonate tubes on each end of it. This will allow me to drill several 3/32" chase bores through the wall of the aluminum ballast tank for the wiring that is now chased through the center tube of the ballast tank. The WTC tube will be 5" diameter. The ballast capacity will be 1000ml.I have a really unusual way to compress the WTC tubes for a high-pressure seal. I will be applying for a patent and will post images soon. My wife is a patent specialist paralegal, so this should be simple.

Water is conductive to a degree, so if you have a very sensitive input that's amplified, you can sense a small short across a pair of probes. The OTW system uses three probes, with one common and two other probes to detect when the tank is empty or full. These probes are usually fed with an AC current so they don't plate-up.

Sounds a bit like over engineering to me with all that aluminium. The OTW works on fairly low pressures, and acrylic only gives problems if you drop it on a hard surface. Polycarbonate definitely is tougher, but it scratches a lot easier, and here in the UK is much more expensive, hence why clear modules tend to be fashioned from acrylic.

You have convinced me to only change out the broken end tube with acrylic material.Thanks.I will save my aluminum ballast tube for a scratch build for my other hulls.I do have a spare eFlite 245KV motor and 120amp Castle Hydra ESC that can exchange for the stock drive. I plan to use internal Lipo batteries under the tray, instead of external pack.